Purpose: To examine the retinal nerve fiber layer (RNFL) ophthalmoscopically, to search for localized RNFL defects, and to assess factors associated with RNFL visibility in a population-based setting.
Methods: The population-based cross-sectional Beijing Eye Study 2006 included 3251 subjects. Using color fundus photographs, RNFL visibility was assessed in grades from 0 to 8 in 8 fundus sectors. Localized RNFL defects were defined as wedge-shaped defects running towards the optic disc.
Results: After exclusion of subjects with optic media opacities, 2602 subjects (mean age: 58.1±9.0 years) were included. RNFL visibility score was highest (P<0.001) in the temporal inferior region, followed by the temporal superior region, nasal superior region, and nasal inferior region. In multivariate analysis, higher RNFL visibility score was associated with younger age (P<0.001; standardized coefficient beta: -0.44; regression coefficient B: -0.22; 95%CI: -0.24, -0.20), female gender (P<0.001; beta: 0.11; B: 1.00; 95%CI: 0.67, 1.32), higher blood concentration of low-density lipoproteins (P = 0.002; beta: 0.07; B: 0.34; 95%CI: 0.13, 0.56), absence of dyslipidemia (P = 0.001; beta: -0.07; B: -0.58; 95%CI: -0.93, -0.24), lower blood glucose concentration (P = 0.006; beta: -0.05; B: -0.14; 95%CI: -0.24, -0.04), hyperopic refractive error (P<0.001; beta: 0.15; B: 0.45; 95%CI: 0.34, 0.56), smaller optic disc size (P<0.001; beta: -0.08; B: -0.72; 95% CI: -1.04, -0.40), absence of glaucomatous optic neuropathy (P<0.001; beta: -0.06; B: -2.69; 95%CI: -4.18, -1.21) and absence of non-glaucomatous optic nerve damage (P = 0.001; beta: -0.06; B: -4.80; 95%CI: 0. -7.64, -1.96). Localized RNFL defects were detected in 96 subjects (prevalence:3.7±0.45% (95% confidence interval (CI): 3.0, 4.4). In multivariate analysis, prevalence of localized RNFL defects was associated with higher blood pressure (P<0.001; odds ratio (OR): 1.07; 95%CI: 1.03, 1.10), higher concentration of low-density lipoproteins (P = 0.01; OR: 1.42; 95%CI: 1.08, 1.85), higher prevalence of glaucomatous optic neuropathy (P<0.001; OR: 46.8; 95%CI: 19.4, 113) and diabetic retinopathy (P = 0.002; OR: 3.20; 95%CI: 1.53, 6.67), and lower total RNFL visibility (P<0.001; OR: 0.92; 95%CI: 0.88, 0.96).
Conclusions: In Chinese aged 45+ years, a decreased RNFL visibility was associated with older age, male gender, dyslipidemia, hyperglycemia, myopia, larger optic disc, and glaucomatous or non-glaucomatous optic neuropathy. Localized RNFL defects (prevalence: 3.7±0.45%) were correlated mainly with higher blood pressure, higher concentration of low-density lipoproteins, glaucomatous optic neuropathy and diabetic retinopathy. These data are helpful for the routine ophthalmoscopic examination of the RNFL.